1. Field of the Invention
Embodiments in accordance with the present invention relate to methods and systems for fall detection and fall prevention of persons, for example elderly hospital patients. However, embodiments may be useful in for other problems, e.g., problems in which it is useful to detect that a monitored person or object is in an unexpected or unsafe physical orientation, or has been in an unchanged physical orientation for too long.
2. Description of Related Art
Certain persons such as hospital patients, and in particular elderly hospital patients, are susceptible to falls. Such persons may be weak, may have brittle bones, may have an impaired sense of balance, may have impaired judgment to avoid physically risky situations in their condition, may lack the requisite physical strength to prevent a fall and/or brace themselves during a fall, and so forth. A fall for such persons may be catastrophic and often, if not immediately fatal, can lead to quick deterioration in condition and even death. Therefore, improved systems and methods for fall prevention and detection are acutely needed.
Known systems and methods to prevent and detect falls suffer shortcomings such as a lack adequate sensitivity and an inherently high false alarm rate.
For example, one method of the known art to prevent falls is the usage of side bed rails to prevent a patient from exiting a bed unsupervised. This method is considered extremely restrictive and can cause patients to feel imprisoned. This method may have little usefulness for patients who are not confined to bed.
Another method of the known art to prevent and/or detect falls includes the usage of accelerometers to detect an impact of a patient's body with the floor. Such a method has proven to be quite poor in reliably detecting a fall for at least two reasons. First, a fall may happen with very little acceleration depending on the way the person falls and the exact position of the accelerometer on the patient body. For example, an accelerometer on a lower leg portion may be expected to experience a relatively lower acceleration during a fall as compared to an accelerometer on an upper portion of the body such as the head or shoulders. Second, an accelerometer may be susceptible to false alarms caused by, e.g., bumping a patient, bumping a bed in which a patient is laying, vibrations such as may be caused by raising or lowering the bed or portions thereof (e.g., side rails), transporting a patient in a wheelchair, elevator start/stop, and so forth. High impact of the accelerometer with substantially anything may cause high acceleration and may be difficult to differentiate from an actual fall.
Another method of the known art to prevent and/or detect falls involves using video, or a succession of still pictures, and coupled with sophisticated image processing. These methods are complex and expensive. In addition they have very limited area of coverage, e.g., just the bed and immediately adjacent area, unless an entire living area is monitored with cameras. Even with such video surveillance, the effectiveness of such methods (e.g., a probability of detection and/or a probability of false alarm) is not proven.
Another method of the known art to prevent and/or detect falls involves using a highly accurate real time location system (“RTLS”) such as those based upon ultra wide band (“UWB”) signals, in order to be able to detect falls based on the location of the UWB tag (e.g., height above the floor). However, UWB technology by itself is immature and relatively unreliable. Furthermore, height of the tag, by itself, is not a reliable indicator of a patient fall.